Electromagnetic deflecting means



April 1958 J. M. N. HANLET ELECTROMAGNETIC DEFLECTING MEANS Filed June29, 1954 F|G.3 FIG.4 FIGS INVEN TOR. (C) JACQUES MARIE NOEL HANLETFl'G.9

A T ran 51E Y United States Patent ELECTROMAGNETIC nnrnacrmo MEANSJacques Marie Noel Hanlet, Paris, France, assignor to J. Visseaux S. A.,Paris, France Application June 2a, 1954, Serial No. 440,156.

Claims priority, application France September 24, 1953 7 Claims. (Cl.313- 76) The present invention relates to an improved electromagneticdeflecting means and to the manufacture thereof for deflecting with ahigh degree of efficiency and without any substantial distorting effectthe electron beam of a cathode ray tube, it is therefore an object ofthe invention to provide an electromagnetic deflecting means adapted tocover the entire angle of 360 around the neck oi the cathode ray tube intwo halves each covering 180.

A further object of the invention is to provide such an improvedstructure of electromagnetic deflecting means that it may advantageouslybe manufactured by a so-called printed circuit process.

An improved electromagnetic deflecting means according to the inventionis mainly characterised in that it consists of at least one pair ofcoils each spiralled turns of wire extending over a half cylindricalsurface and both so serially connected by their outer respective turnsthat their directions of coiling are opposite with respect to eachother; the spiral turns of each coil are so shaped as to avoid anysubstantial portion thereof extending both parailel to the axis of thecylindrical surface and to any transverse generatrix of this surface.

These and other objects of the invention will be described in detailwith reference to the accompanying drawings, wherein:

Fig. 1 schematically shows a conventional arrangement of anelectromagnetic deflecting coil means around the neck of a cathode raytube;

Fig. 2 schematically shows another known arrangement of such anelectromagnetic deflecting means;

Fig. 3 shows a theoretical development in a flat plane of anelectromagnetic deflecting means such as shown in Fig. 1;

Figs. 4 and 5 show two forms of actual development in a flat plane of anelectromagnetic deflecting means according to the invention;

Figs. 6 and 7 illustrate diagrams concerning a first method ofmanufacturing an electromagnetic deflecting means according to theinvention;

Fig.8 illustrates a diagram concerning a second method of manufacturingan electromagnetic deflecting means according to the invention; and,

Fig. 9 at (a), (b) and at (a) ('b) and (a) top rear and cross sectionviews respectively; views of coil elements and their assembly of'suchelectromagnetic deflecting means in the from of a pile such as shown inFig. 8, before their application upon the neck of a cathode ray tube.

In the representations of Figs. 1 and 2 in the interest of clarity asingle turn of wire has been shown for each coil. Similarly, the actualnumber of turns of wire has been reduced in the foliowing figures.

in Figs. 1 to 5, the reference D denotes either the deflection plane orits intersection line with the plane of the drawing, and the reference Hsimilarly denotes the orthogonal plane thereof, here considered to be ahorizontal plane, or its intersection line with the plane of 2,831,136Patented Apr. 15, 1958 ice the drawing. The deflecting means is supposedto cause the lateral deflection of an electron beam the axis of which isindicated by the line X--X in its rest position.

All the intersection lines shown in Figs. 3 to 5 must be considered asbeing taken along generatrices of cylinder it of Figs. 1 and 2. Thiscylinder represents either the neck of a cathode ray tube or acylindrical insulating support for the electromagnetic deflecting means.

In the form of Fig. 1, each turn of Wire of the defleeting means is suchthat it presents two sides parallel to the direction XX and two arcuatesides, each approximately covering l around the neck of the tube, andextending in respective planes orthogonal to axis XX, The longitudinalside 2 of the upper turn of wire and the corresponding side 6 of thelower turn cooperate to form an electromagnetic dipole, through whichthe deflection control current flows in identical directions. Theopposite sides 3 and 7 similarly cooperate but the direction of thecurrent therethrough is the reverse of that of the current through thesides 2 and 6. The arcuate sides 4-5 of the upper turn, and 8-9 of thelower turn are quite useless for deflecting purposes; they alsointroduce, as weil known, deleterious effects in the structure of theelectron beam passing through the deflecting arrangement: at both endsof this arrangement, this electron beam is distorted by the action ofthe magnetic fields due to the presence of such arcuate portions ofturns. Obviously, a quite substantial loss of supply power occurs inportions of turns as 4-5 and 89 since the length of these portions isfairly important in any turn of wire, especially when the deflectingmeans is to ensure wide angle deflections of the controlled electronbeam. For instance, for a cathode ray tube having a deflection angle of70', on either side of the D plane, the useful length of any turn ofwirein Fig. 1 does not reach 35% of its overall length, and in tubes ofrecently developed technique, this overall angle of deflection may bemade as wide as In order to avoid such .end distortions of the magneticdeflecting field, it has been proposed to constitute an electromagneticdeflecting means of a pair of crossed coils, or the like, wherein eachturn of wire consists of an oval or elliptical line. In Fig. 2, it isapparent that the halves 1213 and 14--15 on either side of the H planecomplement each other in a fashion forming two ellipses intersectingeach other and having planes forming an angle 0; the points ofintersection of these ellipses are diametrically opposite with respectto each other, as shown at 10 and 11.

For the same neck diameter, and for the same length along direction XX,both the arrangements of Figs. 1 and 2 have substantially the samesensibility factor. On the other hand, the overall efliciency is greaterfor the arrangement of Fig. 2 since the only useless parts of the turnsare of reduced length and the distorting eflect is also reduced at bothends thereof since the wire lengths generating such distorting fieldshave been reduced.

According to the invention, an electromagnetic deflecting means isprovided with at least one pair of serially connected spirals ofopposite winding direction, the series connection being made by theirrespective outer turns; this pair of spiralled coils form the deflectingmeans shown in a developed flat form in Figs. 3 to 5, and morespecifically, in order to avoid any loss of deflecting power and anydistorting end fields, in the developed flat form of Fig. 5. In Fig. 5the spirals consist of rhombic turns of wire having one diagonalextending along the horizontal or axial direction and the other diagonalextending along the orthogonal direction which, when shaped into arcuateform, will be the direction of the circumference of the neck of thecathode ray tube which is to cooperate with such a deflecting means; thespan of the di- 3 agonal of each spiral extends transversely to such anextent that it will cover 180 on the neck of the cathode ray tube.

In order to carry out the invention, it is also provided to haverecourse to the so-called printed circuit technique; this involvesdepositing or otherwise forming the spiral coils upon a flexibleinsulating backing, then insulating its bare metallised face, andbending the products thus ob- ,tained around the neck of a cathode raytube or an insulating-spacer surrounding this neck.

Alternatively two other processes may be used for manufacturing suchprinted deflecting means. In the first process, Figs. 6 and 7, a spiralof parallelogrammatic turns of wire is first formed upon a flexibleinsulating backing, such as shown in Fig. 6, and, after insulating itsbare metallised face, this product is folded along the oblique lineindicated in Fig. 6. The result is the presentation shown in Fig. 7,assuming the insulating backings are translucid.

In the second process, the double spiral of metallic turns of wire isdirectly formed on an insulating backing,.as shown in Fig. 8.

An insulating film may then be formed over the exposed surface of suchan element.

In both these processes, the following may be observed. A thin metallicfoil, for instance of a copper foil having a thickness of about 7 of amillimeter, is glued upon a plastic material foil alternativelypreferably, it is coated with a dielectric plastic film on one of itsfaces. This may be obtained by spraying an atomised solution of vinylchloride or methyl-ethyl-cetone over this face. In this solution,preferably about 30% in weight of a material or product is added, havinga higher melting point such as calcium carbonate, anhydrated alumina,silica powder,

The thickness of the dielectric film should or the like. not exceed ofone millimeter and constitute a base support of suitable mechanicalstrength.

After this composite foil has been made, a photosensitive film isdeposited on the bare metal foil and the picture of print, viz. thespiral or spirals, is impressed thereupon. The product is developed,washed and dried. It is then immersed into an acid containing bath untilthe unexposed parts of the metal foil are completely dis-' solved. Thecopper turns remain in relief with respect to the insulating backing anda suspension of colloidal iron in butyl acetate also containing from 15to 20% in weight of collodion, is atomized thereupon. In this operation,the colloidal iron fills the intervals between the copper turns of thespiral or spirals, and as a result the thickness of the composite foilis substantially uniform throughout its area.

In some cases, a single element will suflice to bring a completeelectromagnetic deflecting means. Generally, however, it will benecessary to pile up a plurality of "such double spiralled elements forobtaining a deflecting means of suitable power. In such files, thedouble spiralled coils must be serially interconnected so that thedeflecting current after passing through the two spirals of one element,which are serially connected by their structure, passes in the samedirection through the next element of the pile.

In such a case, and especially in the manufacture of a deflecting meansfrom elements such as shown in Fig. 8, it is further provided to realizetwo sets of elements, such as (a) and (b) in Fig. 9, wherein therelative winding directions are opposite. The connection points orterminals are shown at 16, 17 for the (a) element, and at 18, 19 for the(b) element. For electricaly connecting such elements, a thin solderwill be made between terminals 17 and 19, then for the followingelement, between terminals 16 and 18, and so forth, as shown in part (c)of Fig. 9 at 20. Such solder paint may be made by painting the terminalswith a mixture of rosin and stannic powder, bringing these paintedterminals together and heating the paints by means of a soldering iron.The insulating films 4 will be burned off at these points. After asuitable number of elements has thus been connected, a moderatesqueezing is applied to the pile, in the directions indicated by arrowsin Fig. 9(a). In Fig. 9(a), the file is shown before squeezing.

Such an electromagnetic deflecting structure whether consisting of asingle element or a piling of such elements, pile may be applied at willaround the neck of any cathode ray tube for which it has been designed.As the deflecting current passes through the identical but oppositelywound spirals of each and any element, and due to the high efliciencyand almost complete distortion, there is obtained a substantially higherdegree of uniformity in the controlling magnetic field than withconventional electromagnetic deflecting means.

Having thus described my invention, I claim:

1. In an electromagnetic deflection structure for the neck of a cathoderay tube, at least one flexible sheeted carrier adapted to extendsubstantially around said neck and containing at least one pair ofoppositely wound fiat spiral coils extending over the carrier surface injuxtaposition; the windings of each coil extending over op posite halvesof said neck with the outer windings of said coils being connected inseries; and means for applying deflecting current to said coils at theinner windings; at least the greater part of said windings having anglesother than zero and with the generatrices of said neck.

2. Structure according to claim 1, wherein several pairs of spiral coilssupported on carrier sheets are piled upon each other, each pair ofcoils in said pile being oppositely 'wound with respect to adjacentpairs of coils in said pile,

and means for alternately connecting the center windings of pairs ofspiral coils to diiferent coils in the succeeding pairs of coils of saidpile.

3. Structure according to claim 1, wherein the windings of each coil areof generally circular shape.

4. Structure according to claim 1, wherein the windings of each coil areof generally rectangular parallelogrammatic shape, one diagonal of theparallelograms being substantially parallel to the generatrices of saidcylindrical neck.

being formed of two sections separated by a straight line passingthrough the centers of said parallelograms, said two coil sections beingarranged on two coil portions of said carrier sheet superimposed uponeach other and attached to each other along said straight separationline.

7. Structure according to claim 1, wherein several pairs 'of spiralcoils supported on carrier sheets are piled upon each other, each pairof coils in said pile being oppositely wound with respect to adjacentpairs of coils in said pile, and means for alternately connecting thecenter windings of pairs of spiral coils to different coils insucceeding pairs of said pile, said connecting means including adeformation of the carrier sheets at the points of connection.

References Cited in the file of this patent UNITED STATES PATENTS 11,647,474 Seymour Nov. 1, 1927 1,995,376 Campbell Mar. 26, 19352,237,651 Bruche Apr. 8, 1941 (Other references on following page) 5UNITED STATES PATENTS Urtel Apr. 8, 1941 Mauerer Jan. 13, 1942 OliverApr. 7, 1942 Johnson July 13, 1943 Korte May 7, 1946 Schenau Nov. 1,1955 Reinhard Nov. 20, 1956 OTHER REFERENCES Martin: Printed CrossedField Deflecting Coils, Tele- Tech and Electronic Industries, December1954, pp. 82, 83, 140 and 141.

Brunetti et 211.: Printed Circuit Techniques, National Bureau ofStandards Circular 468, November 15, 1947, pp. 17 and 18.

